Driving assistance devices are known that notify the driver of a vehicle of information on the driving environment of the vehicle, in particular, the state of a traffic light, thereby assisting the driving operation of the vehicle by the driver. Such driving assistance devices provide to the driver, based on signal information on a signal state of a traffic light and a signal cycle, obtained through an optical beacon, driving assists, such as a deceleration assist to decelerate the vehicle, and a run stopping assist to run or stop the vehicle. Patent Document 1 discloses an example driving assistance device that provides driving assistances of the vehicle to the driver in relation to a traffic light based on such signal information.
That is, the driving assistance device disclosed in Patent Document 1 assists the run stopping of the vehicle based on signal cycle information included in signal information obtained from an optical beacon. This driving assistance device includes uncertain cycle information specifying means for specifying uncertain cycle information indicating signal cycle information having an uncertain time that the traffic light changes from a red signal (stop light) to a green signal (forward movement permitting light), and assistance suppressing means for suppressing the run stopping assist for the vehicle to the uncertain cycle information specified by the uncertain cycle information specifying means. Hence, according to the driving assistance device of Patent Document 1, a vehicle driving assist in relation to a traffic light is performed based on signal cycle information, but the execution of the driving assist is suppressed in relation to a traffic light having uncertain signal cycle information.